JP2018018710A - Light source device and display device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve color purity.SOLUTION: A light source device 10 supplies a laser beam to a display panel 30. The light source device 10 includes: a light-emitting device 13 for emitting a laser beam; and a light guide plate 16 disposed so as to receive the laser beam from the light-emitting device 13 at the lateral part thereof and having a step-wise bottom part. The bottom part of the light guide plate 16 has a plurality of reflection surfaces 16B disposed while being aligned in a first direction in which the laser beam proceeds.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a light source device and a display device including the light source device.

  A backlight using a white LED as a light source is known as a backlight for a liquid crystal display panel. Since the LED has a width in the wavelength band, the color purity tends to decrease. Further, since two polarizing plates are used in the liquid crystal display panel, the light intensity output from the liquid crystal display panel is less than half of the light intensity of the backlight.

JP 2012-94540 A

  The present invention provides a light source device capable of improving color purity and a display device including the same.

  A light source device according to one embodiment of the present invention is a light source device that supplies laser light to a display panel, and is disposed so that a light emitting element that emits laser light and a laser beam from the light emitting element are received by a side portion. And a light guide plate having a stepped bottom. The bottom portion of the light guide plate has a plurality of reflecting surfaces arranged in a first direction in which the laser light travels.

  A light source device according to an aspect of the present invention is a light source device that supplies laser light to a display panel, and a light emitting element that emits laser light and a laser beam from the light emitting element are received by a first side portion. A light guide plate disposed on the opposite side of the first side and having a second side made of a Fresnel lens and having a stepped bottom; a reflective film provided to cover the Fresnel lens; It comprises. The bottom portion of the light guide plate has a plurality of reflecting surfaces arranged in a first direction in which the laser light travels.

  A display device according to one embodiment of the present invention includes any one of the light source devices described above and a display panel that modulates laser light from the light source device.

  ADVANTAGE OF THE INVENTION According to this invention, the light source device which can improve color purity, and a display apparatus provided with the same can be provided.

1 is a cross-sectional view of a liquid crystal display device according to a first embodiment. The perspective view of a light source device. The top view of a light source device. Sectional drawing of a light-guide plate. Sectional drawing of a liquid crystal panel. The graph explaining the characteristic of a laser beam and a color filter. The graph explaining the characteristic of the display light after the laser beam from a light source device permeate | transmits a color filter. Sectional drawing of the liquid crystal display device which concerns on the modification of 1st Embodiment. The top view of the light source device which concerns on 2nd Embodiment. Sectional drawing of the light-guide plate which concerns on 2nd Embodiment. Sectional drawing of the liquid crystal display device which concerns on 3rd Embodiment. The top view of the light source device which concerns on 4th Embodiment. Sectional drawing of the light-guide plate which concerns on 4th Embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. However, the drawings are schematic or conceptual, and the dimensions and ratios of the drawings are not necessarily the same as actual ones. Further, even when the same portion is represented between the drawings, the dimensional relationship and ratio may be represented differently. In particular, the following embodiments exemplify an apparatus and a method for embodying the technical idea of the present invention, and the technical idea of the present invention depends on the shape, structure, arrangement, etc. of components. Is not specified. In the following description, elements having the same function and configuration are denoted by the same reference numerals, and redundant description will be given only when necessary.

[1] First Embodiment [1-1] Overall Configuration of Liquid Crystal Display Device FIG. 1 is a cross-sectional view of a liquid crystal display device 1 according to a first embodiment. The liquid crystal display device 1 includes a light source device (backlight) 10 and a liquid crystal panel (liquid crystal display panel) 30.

  The light source device 10 is disposed on the back side of the liquid crystal panel 30, that is, on the side opposite to the display surface (surface on which an image is displayed) of the liquid crystal panel 30 with a predetermined interval, for example. A fixing method between the light source device 10 and the liquid crystal panel 30 is arbitrary, and a special support member or case may be used.

  The light source device 10 functions as a surface light source and supplies planar illumination light to the liquid crystal panel 30. In the present embodiment, the light source device 10 generates illumination light using laser light. The light source device 10 is also called a laser backlight. The light source device 10 includes a case 11, a support member 12, a light emitting element (laser element) 13, an optical system 14, a reflection sheet 15, and a light guide plate 16.

  The case 11 accommodates a plurality of modules included in the light source device 10. The case 11 has a (planar) outer shape as viewed from above, for example, a quadrangle, and has a size and depth that can accommodate a plurality of modules included in the light source device 10. The case 11 is made of metal, for example.

  The support member 12 has a function of holding the light emitting element 13 and the optical system 14 at predetermined positions. The support member 12 is made of resin, for example. The support member 12 can take a complicated shape according to the shape and position of the light emitting element 13 and the optical system 14.

  The light emitting element 13 emits laser light and emits white light. For example, a semiconductor laser is used as the light emitting element 13. White light is generated by, for example, additive color mixing of red, green, and blue laser light, which are the three primary colors of light. In the case of this example, the light emitting element 13 includes a red laser light source, a green laser light source, and a blue laser light source, and generates white light with three colors of light emitted from these. The red laser light source emits monochromatic light (single wavelength light), and the monochromatic light has strong directivity. The same applies to the green laser and the blue laser.

  The optical system 14 receives laser light from the light emitting element 13. The optical system 14 has a function of converting the laser light from the light emitting element 13 into parallel light having substantially the same width as the length of the light guide plate 16 in the Y direction (direction perpendicular to the paper surface of FIG. 1). In FIG. 1, the optical system 14 is simplified and shown in a block diagram. However, as will be described later, the optical system 14 actually includes a plurality of lenses.

  The reflection sheet 15 reflects light toward the liquid crystal panel 30.

  The light guide plate 16 emits the laser light incident from the optical system 14 toward the liquid crystal panel 30. The light guide plate 16 emits linearly polarized light in a predetermined direction toward the liquid crystal panel 30. A specific configuration of the light guide plate 16 for realizing such a function will be described later.

[1-2] Configuration of Light Source Device 10 Next, a specific configuration of the light source device 10 will be described. FIG. 2 is a perspective view of the light source device 10. FIG. 3 is a plan view of the light source device 10.

  The optical system 14 includes a rod lens 14A and a cylindrical lens 14B. The rod lens 14A is a rod-shaped (cylindrical) lens that extends in a direction perpendicular to the XY plane. The rod lens 14A is disposed on the optical path of the laser light from the light emitting element 13, and is disposed so as to receive the laser light on its curved surface. The rod lens 14A has a short focal length and emits laser light at a predetermined radiation angle (expansion angle). By appropriately setting the diameter and refractive index of the rod lens 14A, the radiation angle of the laser light emitted from the rod lens 14A can be set as appropriate.

  The cylindrical lens 14B receives the laser light from the rod lens 14A. The cylindrical lens 14B is a plano-convex cylindrical lens having a curved surface formed of a part of a cylindrical shape and a linear plane. The cylindrical lens 14B has a function of converting the laser light from the rod lens 14A into parallel light. The width of the parallel light can be appropriately set according to the distance between the rod lens 14A and the cylindrical lens 14B.

  The light guide plate 16 receives the laser light from the cylindrical lens 14B. FIG. 4 is a cross-sectional view of the light guide plate 16. In FIG. 4, an enlarged view and a perspective view of a part of the light guide plate 16 are added.

  The bottom of the light guide plate 16 is configured in a step shape and has a plurality of steps. Each step is composed of a staircase surface 16A and a reflecting surface 16B intersecting the step surface 16A. The plurality of reflection surfaces 16B are arranged side by side in the X direction, and each of the plurality of reflection surfaces 16B extends in the Y direction. Each of the plurality of reflecting surfaces 16 </ b> B reflects the laser light toward the liquid crystal panel 30. Each of the plurality of reflecting surfaces 16B is inclined by an angle θ1 with respect to the vertical direction. Each of the plurality of step surfaces 16A is inclined by an angle θ2 with respect to the horizontal direction.

  The light emitting element 13 emits laser light downward by an angle θ1 with respect to the horizontal direction so that the laser light emitted by the light emitting element 13 is substantially parallel to the step surface 16A. The support member 12 shown in FIG. 1 supports the light emitting element 13 so that the light emitting element 13 faces downward by an angle θ1. Further, the support member 12 supports the rod lens 14A so that the laser light from the light emitting element 13 is incident on the curved surface of the rod lens 14A substantially perpendicularly, that is, the rod lens 14A is inclined downward by an angle θ1. . Similarly, the support member 12 supports the cylindrical lens 14B so that the laser light from the rod lens 14A is perpendicularly incident on the incident surface of the cylindrical lens 14B, that is, the cylindrical lens 14B is inclined downward by an angle θ1. To do.

[1-3] Configuration of Liquid Crystal Panel 30 Next, an example of the configuration of the liquid crystal panel 30 will be described. FIG. 5 is a cross-sectional view of the liquid crystal panel 30.

  The liquid crystal panel 30 includes a TFT substrate 31 on which TFTs, pixel electrodes, and the like are formed, a color filter substrate (CF substrate) 32 on which color filters, common electrodes, and the like are formed and disposed to face the TFT substrate 31, and a TFT substrate 31. And a liquid crystal layer 33 sandwiched between the CF substrates 32. Each of the TFT substrate 31 and the CF substrate 32 is composed of a transparent substrate (for example, a glass substrate). The TFT substrate 31 is disposed on the light source device 10 side, for example, and illumination light from the light source device 10 enters the liquid crystal layer 33 from the TFT substrate 31 side. Of the two main surfaces of the liquid crystal panel 30, the main surface opposite to the light source device 10 is the display surface of the liquid crystal panel 30.

  The liquid crystal layer 33 is composed of a liquid crystal material sealed by a sealing material 34 that bonds the TFT substrate 31 and the CF substrate 32 together. A region surrounded by the sealing material 34 is a display region of the liquid crystal panel 30. In the liquid crystal material, the alignment of liquid crystal molecules is manipulated according to the electric field applied between the TFT substrate 31 and the CF substrate 32, and the optical characteristics change.

  For example, a VA (Vertical Alignment) mode is used as the liquid crystal mode. However, the present invention is not limited to this, and various liquid crystal modes such as a TN (Twisted Nematic) mode and a homogeneous mode can be used. As a display mode, a normally black mode (mode in which light transmittance or luminance in the off state is lower than that in the on state) may be used, or normally white mode (light transmittance in the off state). Alternatively, a mode in which the luminance is higher than that in the on state) may be used. The display mode can be changed by appropriately setting the polarization direction by the polarizing plate and the phase difference of the liquid crystal layer.

  The sealing material 34 is made of, for example, an ultraviolet curable resin, a thermosetting resin, or an ultraviolet / heat combination type curable resin, and is applied to the TFT substrate 31 or the CF substrate 32 in the manufacturing process, and then irradiated with ultraviolet rays or heated. Cured. In the sealing material 34, a gap material such as glass fiber or glass beads for dispersing a distance (that is, a gap) between the TFT substrate and the CF substrate to a predetermined value is dispersed. In addition to or instead of mixing the gap material into the seal material 34, the gap material may be arranged in a peripheral region located around the image display region.

  A plurality of switching elements (active elements) 35 are provided on the liquid crystal layer 33 side of the TFT substrate 31. As the switching element 35, for example, a TFT (Thin Film Transistor) is used, and an n-channel TFT is used. The TFT 35 includes a gate electrode electrically connected to the scanning line GL, a gate insulating film provided on the gate electrode, a semiconductor layer (for example, an amorphous silicon layer) provided on the gate insulating film, and a semiconductor layer. A source electrode and a drain electrode provided in contact with each other and spaced apart from each other; The source electrode is electrically connected to the signal line SL.

  An insulating layer 36 is provided on the TFT 35. A plurality of pixel electrodes 37 are provided on the insulating layer 36. A contact plug 38 electrically connected to the pixel electrode 37 is provided in the insulating layer 36 and on the drain electrode of the TFT 35.

  A color filter 39 is provided on the liquid crystal layer 33 side of the CF substrate 32. The color filter 39 includes a plurality of coloring filters (coloring members), and specifically includes a plurality of red filters 39-R, a plurality of green filters 39-G, and a plurality of blue filters 39-B. A general color filter is composed of three primary colors of light, red (R), green (G), and blue (B). A set of three colors R, G, and B adjacent to each other is a display unit (pixel), and any single color portion of R, G, B in one pixel is a minimum called a subpixel (subpixel). It is a drive unit. The TFT 35 and the pixel electrode 37 are provided for each subpixel. In the following description, a subpixel is referred to as a pixel unless it is particularly necessary to distinguish between a pixel and a subpixel.

  A black matrix (light-shielding film) 40 for light shielding is provided at the boundary between the red filter 39-R, the green filter 39-G, and the blue filter 39-B, and the boundary between the pixels (sub-pixels). That is, the black matrix 40 is formed in a mesh shape. For example, the black matrix 40 has a function of shielding unnecessary light between the coloring members and improving the contrast.

  A common electrode 41 is provided on the color filter 39 and the black matrix 40. The common electrode 41 is formed in a planar shape over the entire display area of the liquid crystal panel 30.

  A polarizing plate (polarizer) 42 is provided on the opposite side of the CF substrate 32 from the liquid crystal layer 33. The polarizing plate 42 extracts light having a vibrating surface in one direction parallel to the transmission axis, that is, light having a linearly polarized light state, from light having a vibrating surface in a random direction. The transmission axis of the polarizing plate 42 is set so as to be substantially orthogonal to the vibration direction (also referred to as polarization direction or polarization axis) of the laser light emitted from the light source device 10. In the present embodiment, only one polarizing plate is necessary, and no polarizing plate is provided on the TFT substrate 31 side.

  The pixel electrode 37, the contact plug 38, and the common electrode 41 are configured by transparent electrodes, and for example, ITO (indium tin oxide) is used. As the insulating layer 36, a transparent insulating material is used, for example, silicon nitride (SiN).

[1-4] Operation Next, the operation of the liquid crystal display device 1 configured as described above will be described.
As shown in FIG. 3, the light emitting element 13 emits laser light that vibrates in the horizontal direction (Y direction) and has high directivity. The laser light from the light emitting element 13 is diffused by the rod lens 14A so as to have a predetermined radiation angle. The laser light from the rod lens 14A is converted into parallel light by the cylindrical lens 14B. The parallel light from the cylindrical lens 14B enters the light guide plate 16 from its side (side surface).

  Further, as shown in FIG. 4, the light emitting element 13 and the optical system 14 (rod lens 14A and cylindrical lens 14B) emit laser light downward by an angle θ1 with respect to the horizontal direction. Therefore, the parallel light from the cylindrical lens 14B enters the side portion of the light guide plate 16 so as to travel downward by an angle θ1 with respect to the horizontal direction.

  Subsequently, the laser light in the light guide plate 16 reaches the bottom of the light guide plate and is reflected upward by the plurality of reflection surfaces 16 </ b> B formed on the bottom of the light guide plate 16. Further, since the traveling direction of the laser light in the light guide plate 16 is substantially parallel to the plurality of step surfaces 16A formed at the bottom of the light guide plate 16, the laser light is efficiently incident on the plurality of reflection surfaces 16B. And reflected.

  Further, as shown in FIG. 2, a reflection sheet 15 is provided below the light guide plate 16. Therefore, the laser light transmitted and diffused to the lower side of the light guide plate 16 is reflected by the reflection sheet 15 and enters the light guide plate 16 again. Thereby, the utilization efficiency of a laser beam can be improved.

  The laser light from the light source device 10 serves as a surface light source and has a polarization direction in the Y direction. Laser light from the light source device 10 enters the liquid crystal panel 30. The polarization direction of the laser light from the light guide plate 16 is substantially orthogonal to the transmission axis of the polarizing plate 42. Therefore, normally black display is realized according to the light modulation by the liquid crystal layer 33. Thereby, the liquid crystal panel 30 can display a desired image.

  FIG. 6 is a graph for explaining the characteristics of the laser light and the color filter 39. The horizontal axis in FIG. 6 represents wavelength (nm), and the vertical axis in FIG. 6 represents relative intensity (%). The relative intensity is an intensity when the maximum value is 100%. FIG. 6 shows three types of monochromatic light included in the laser light emitted from the light emitting element 13, and characteristics of the red filter 39-R, the green filter 39-G, and the blue filter 39-B.

  FIG. 7 is a graph for explaining the characteristics of the display light after the laser light from the light source device 10 passes through the color filter 39. Light in a region where the intensity of the laser light from the light source device 10 and the characteristics of the color filter 39 overlap becomes display light of the liquid crystal panel 30. Thus, in the present embodiment, since laser light is used as the light source, it is possible to realize image display with high color purity.

[1-5] Modified Example FIG. 8 is a cross-sectional view of the liquid crystal display device 1 according to a modified example of the first embodiment. The reflective film 17 may be provided on the side portion (side surface) of the light guide plate 16 far from the light emitting element 13.

  The reflection film 17 reflects the light emitted from the side surface in contact with the reflection film 17 of the light guide plate 16 into the light guide plate 16 again. Thereby, the utilization efficiency of a laser beam can be improved.

[1-6] Effects of First Embodiment As described in detail above, in the first embodiment, the liquid crystal display device 1 includes the light source device 10 that supplies laser light to the liquid crystal panel 30. The light source device 10 includes a light emitting element 13 that emits laser light, and a light guide plate 16 that is disposed so as to receive the laser light from the light emitting element 13 at the side and has a stepped bottom. The bottom of the light guide plate 16 has a plurality of reflection surfaces 16B arranged side by side in the first direction in which the laser light travels. Tilt in one direction.

  Therefore, according to the first embodiment, color purity can be improved and light intensity can be improved as compared with the case where a white LED is used as a light source. Moreover, high color reproducibility is realizable by using a laser as a light source.

  The light source device 10 also includes an optical system 14 (rod lens 14A and cylindrical lens 14B) that converts laser light from the light emitting element 13 into parallel light. Thereby, the light source device 10 can function as a surface light source.

  Further, the light source device 10 can generate linearly polarized light in a predetermined direction. Therefore, the liquid crystal panel 30 does not need to include a polarizing plate on the light source device 10 side. Thereby, since the fall of the light intensity by a polarizing plate can be suppressed, it can suppress that the light intensity of the image which the liquid crystal display device 1 displays falls.

  Moreover, since the number of polarizing plates can be reduced, manufacturing cost can be reduced. Furthermore, a diffusion sheet for diffusing light for backlight is not necessary.

[2] Second Embodiment The second embodiment is a configuration example of the light source device 10 having a polarization direction different from that of the first embodiment. FIG. 9 is a plan view of the light source device 10 according to the second embodiment. FIG. 10 is a cross-sectional view of the light guide plate 16 according to the second embodiment.

  As shown in FIGS. 9 and 10, the light emitting element 13 oscillates in a direction substantially perpendicular to the XY plane and emits a highly directional laser beam. The light guide plate 16 reflects the laser beam incident from the light emitting element 13 through the optical system 14 to the liquid crystal panel 30 side. Thereby, the laser light from the light source device 10 becomes a surface light source and has a polarization direction in the X direction.

  The polarizing plate 42 of the liquid crystal panel 30 is configured such that its transmission axis is in the Y direction. The polarization direction of the laser light from the light guide plate 16 is substantially orthogonal to the transmission axis of the polarizing plate 42. Therefore, normally black display is realized according to the light modulation by the liquid crystal layer 33. Thereby, the liquid crystal panel 30 can display a desired image.

  Thus, in 2nd Embodiment, the polarization direction of the light source device 10 and the liquid crystal panel 30 can be set to a different direction from 1st Embodiment.

[3] Third Embodiment FIG. 11 is a cross-sectional view of a liquid crystal display device 1 according to a third embodiment. On the opposite side of the TFT substrate 31 from the liquid crystal layer 33, a reflective polarizing plate (reflective polarizer) 43 is provided. In FIG. 11, transmission axes when the polarizing plate 42 and the reflective polarizing plate 43 are viewed in plan view are added. The configuration other than the reflective polarizing plate 43 is the same as that of the first embodiment.

  The reflective polarizing plate 43 has a transmission axis and a reflection axis that are orthogonal to each other in a plane orthogonal to the traveling direction of light. The reflection-type polarizing plate 43 transmits linearly polarized light (linearly polarized light component) having a vibration surface parallel to the transmission axis out of light having a vibration surface in a random direction, and has a vibration surface parallel to the reflection axis. Reflects linearly polarized light (linearly polarized light component). The transmission axis of the reflective polarizing plate 43 is parallel to the polarization direction of the light source device 10 and is orthogonal to the transmission axis of the polarizing plate 42.

  The linearly polarized light from the light source device 10 passes through the reflective polarizing plate 43 and enters the liquid crystal layer 33. Thereby, a sufficiently polarized laser beam can be obtained. For example, when the polarized light is not sufficient with only the light source device 10, more desirable linearly polarized light can be obtained by using the reflective polarizing plate 43.

  Further, the laser light reflected by the reflective polarizing plate 43 is reflected by the reflection sheet 15 of the light source device 10 and reused.

  Note that the reflective polarizing plate 43 of the third embodiment may be applied to the second embodiment. In this case, the transmission axis of the reflective polarizing plate 43 is set parallel to the polarization direction of the light source device 10.

[4] Fourth Embodiment The fourth embodiment is another configuration example of the light source device 10 and generates a surface light source of laser light by utilizing Fresnel reflection on the light guide plate.

  FIG. 12 is a plan view of the light source device 10 according to the fourth embodiment. FIG. 13 is a cross-sectional view of the light guide plate 16 according to the fourth embodiment. Unlike the first embodiment, the light emitting element 13 emits laser light in the horizontal direction. Therefore, the laser light from the light emitting element 13 enters the side surface of the light guide plate 16 perpendicularly.

  The light guide plate 16 includes a light diffusion portion 16C on the side surface on the light emitting element 13 side. The light diffusion portion 16C is a semi-cylindrical lens extending in a direction perpendicular to the XY plane. The light diffusing unit 16C is disposed on the optical path of the laser light from the light emitting element 13, and is disposed so as to receive the laser light on its curved surface. The light diffusing unit 16C has a short focal length, and diffuses laser light at a predetermined radiation angle (expansion angle). By appropriately setting the radius and refractive index of the light diffusion portion 16C, the radiation angle of the laser light diffused by the light diffusion portion 16C can be appropriately set. Note that the rod lens 14A shown in the first embodiment may be used in place of the light diffusing unit 16C.

  The light guide plate 16 includes a Fresnel lens 16D on the side surface opposite to the light diffusion portion 16C. The Fresnel lens 16D has a function of converting the laser light diffused by the light diffusion unit 16C into parallel light. A reflective film 50 is provided on the side surface of the Fresnel lens 16D. The reflection film 50 reflects the laser light transmitted through the light guide plate 16 into the light guide plate 16 again.

  The side surface of the Fresnel lens 16D is inclined downward by an angle θ2. As a result, the Fresnel lens 16D and the reflective film 50 can reflect the laser light incident on the Fresnel lens 16D in the horizontal direction downward by an angle θ2.

  The bottom of the light guide plate 16 is configured in a step shape and has a plurality of steps. Each step is composed of a staircase surface 16A and a reflecting surface 16B intersecting with the staircase surface 16A. The plurality of reflection surfaces 16B are arranged side by side in the X direction, and each of the plurality of reflection surfaces 16B extends in the Y direction. Each of the plurality of reflecting surfaces 16 </ b> B reflects the laser light from the Fresnel lens 16 </ b> D toward the liquid crystal panel 30. Each of the plurality of reflecting surfaces 16B is inclined by an angle θ1 with respect to the vertical direction. Each of the plurality of step surfaces 16A is inclined by an angle θ2 with respect to the horizontal direction. The inclination of the step of the light guide plate 16 in the fourth embodiment is opposite to that in the first embodiment. Thereby, the laser light from Fresnel lens 16D can be efficiently incident on the plurality of reflecting surfaces 16B.

  Similar to the first embodiment, a reflective sheet 15 is provided below the light guide plate 16.

(Operation)
Next, the operation of the liquid crystal display device 1 configured as described above will be described.
As shown in FIGS. 12 and 13, the light emitting element 13 emits laser light that vibrates in the horizontal direction (Y direction) and has high directivity. The laser light from the light emitting element 13 is diffused by the light diffusion portion 16C so as to have a predetermined radiation angle. The laser light from the light diffusion portion 16C is converted into parallel light by the Fresnel lens 16D. The parallel light is reflected by the reflective film 50 and passes through the light guide plate 16 again. Further, the Fresnel lens 16D and the reflection film 50 reflect the laser light from the light diffusion portion 16C downward by an angle θ1 with respect to the horizontal direction.

  Subsequently, the laser light in the light guide plate 16 is reflected upward by a plurality of reflection surfaces 16 </ b> B formed at the bottom of the light guide plate 16. Further, since the traveling direction of the laser light in the light guide plate 16 is substantially parallel to the plurality of step surfaces 16A formed at the bottom of the light guide plate 16, the laser light is efficiently incident on the plurality of reflection surfaces 16B. And reflected.

  Further, similarly to the first embodiment, a reflective sheet 15 is provided below the light guide plate 16. Therefore, the laser light transmitted and diffused to the lower side of the light guide plate 16 is reflected by the reflection sheet 15 and enters the light guide plate 16 again. Thereby, the utilization efficiency of a laser beam can be improved.

  The laser light from the light source device 10 serves as a surface light source and has a polarization direction in the Y direction. Laser light from the light source device 10 enters the liquid crystal panel 30. Thereby, the liquid crystal panel 30 can display a desired image.

  Therefore, according to the fourth embodiment, the same effect as that of the first embodiment can be obtained. Further, the size of the light source device 10 in the X direction can be reduced as compared with the first embodiment. The second and third embodiments can be applied to the fourth embodiment.

  In the first to fourth embodiments, a liquid crystal panel is described as an example of the display panel. The display panel is not limited to a liquid crystal panel, and various display panels that require a backlight and can be modulated using light received from the backlight can be used.

  In the present specification, the term “parallel” is preferably completely parallel, but is not necessarily strictly parallel, and includes those that can be regarded as substantially parallel in view of the effects of the present invention. An error that may occur in the manufacturing process may be included. In addition, “vertical” does not necessarily have to be strictly vertical, and includes what can be regarded as substantially vertical in view of the effects of the present invention, and may include errors that may occur in the manufacturing process. Good.

  In the present specification, a sheet, a plate, a film, and the like are expressions illustrating the members, and are not limited to the configurations. For example, the polarizing plate is not limited to a plate-like member, and may be a film having other functions described in the specification or other members.

  The present invention is not limited to the above embodiment, and can be embodied by modifying the constituent elements without departing from the scope of the invention. Further, the above embodiments include inventions at various stages, and are obtained by appropriately combining a plurality of constituent elements disclosed in one embodiment or by appropriately combining constituent elements disclosed in different embodiments. Various inventions can be configured. For example, even if some constituent elements are deleted from all the constituent elements disclosed in the embodiments, the problems to be solved by the invention can be solved and the effects of the invention can be obtained. Embodiments made can be extracted as inventions.

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device, 10 ... Light source device, 11 ... Case, 12 ... Support member, 13 ... Light emitting element, 14 ... Optical system, 14A ... Rod lens, 14B ... Cylindrical lens, 15 ... Reflective sheet, 16 ... Light guide plate, 16A ... Stair surface, 16B ... Reflective surface, 16C ... Light diffusion part, 16D ... Fresnel lens, 17 ... Reflective film, 30 ... Liquid crystal panel, 31 ... TFT substrate, 32 ... CF substrate, 33 ... Liquid crystal layer, 34 ... Sealing material , 35 ... switching element, 36 ... insulating layer, 37 ... pixel electrode, 38 ... contact plug, 39 ... color filter, 40 ... black matrix, 41 ... common electrode, 42 ... polarizing plate, 43 ... reflective polarizing plate, 50 ... Reflective film.

Claims (11)

A light source device for supplying laser light to a display panel,
A light emitting element that emits laser light;
A light guide plate that is disposed so as to receive laser light from the light emitting element at a side portion and has a stepped bottom, and
The light source device according to claim 1, wherein a bottom portion of the light guide plate has a plurality of reflection surfaces arranged side by side in a first direction in which the laser light travels.   2. The light source device according to claim 1, wherein each of the plurality of reflection surfaces is inclined in the first direction with respect to a normal line on an upper surface of the light guide plate.   The light source device according to claim 1, further comprising an optical system that is disposed between the light emitting element and the light guide plate and converts laser light from the light emitting element into parallel light.   The light source device according to claim 3, wherein the optical system includes a rod lens that diffuses laser light from the light emitting element and a cylindrical lens that converts laser light from the rod lens into parallel light. . A light source device for supplying laser light to a display panel,
A light emitting element that emits laser light;
A light guide element is disposed so as to receive laser light from the light emitting element at a first side portion, is disposed on a side opposite to the first side portion, has a second side portion made of a Fresnel lens, and has a stepped bottom. A light plate,
A reflective film provided so as to cover the Fresnel lens,
The light source device according to claim 1, wherein a bottom portion of the light guide plate has a plurality of reflection surfaces arranged side by side in a first direction in which the laser light travels.   6. The light source device according to claim 5, wherein each of the plurality of reflecting surfaces is inclined in a second direction opposite to the first direction with respect to a perpendicular line of an upper surface of the light guide plate.   The light source device according to claim 5, further comprising a diffusion unit that is provided on the first side portion of the light guide plate and diffuses laser light from the light emitting element.   The light source device according to claim 1, further comprising a reflective film disposed so as to face a bottom portion of the light guide plate. A light source device according to any one of claims 1 to 8,
A display device comprising: a display panel that modulates laser light from the light source device.   The display device according to claim 9, further comprising a polarizing plate provided on the opposite side of the display panel from the light source device. A reflection type polarizing plate provided on the side of the display panel facing the light source device and having a transmission axis and a reflection axis intersecting each other;
The display device according to claim 9, wherein a transmission axis of the reflective polarizing plate is substantially parallel to a polarization direction of the light source device.